The present invention relates generally to air sampling devices used for gathering and analyzing trace elements from a particular environment such as a suspected contaminated area and, more particularly, to several embodiments of a lightweight, portable multi-tube sampler device capable of acquiring multiple samples of trace elements such as concentrations of chemical agents and toxic industrial chemicals for subsequent analysis by a mass spectrometer or other analyzing unit at a remote location.
There are many applications in which it is desirable to collect and capture air samples from a particular environment suspected of contamination such as collecting air samples in potential hazardous chemical release situations, collecting vapor samples from bulk chemical storage locations, and/or collecting air samples in potential chemical agent release situations. Many different types of sampling devices exist today for capturing samples of trace elements or contaminants from a particular environment and, once collected, such samples are analyzed to determine the nature of the chemicals involved, the level of contamination in the air, and the degree of risk personnel may be exposed to in the contaminated area. Some of the known devices utilize a single concentrator tube to acquire samples for trace analysis, while others include multiple concentrator tubes or capture traps for collecting such contaminants. In addition, some known devices provide for immediate analysis whereas others allow the concentrator tubes to be removed for analysis at a remote location.
There are also known existing portable sampling devices for use in the field. One such example of an automatic multi-sorbent tube air sampler is disclosed in U.S. Pat. No. 6,477,906. This sampling system includes a plurality of tubes connected to a single multi-port valve wherein each tube is connected through the valve by means of pairs of valve ports, the inlet and outlet ports of each respective tube being positioned in adjacent ports associated with the multi-port valve resulting in a multi-tube design. The multi-port valve is constructed and operated in a predetermined sequence to create a flow path through the multi-port valve wherein the flow path directs an air sample to only one tube at a given time. The multi-port valve also includes a plurality of park positions between the respective ports wherein the valve can be set in a corresponding park position between ports thereby isolating all tubes in this position from the flow path while at the same time requiring minimum movement of the valve to the next operative position for the next tube when a sample is to be taken. In addition, each sample tube is mounted on coiled tubing springs so that a sample tube can be desorbed and analyzed while the sample tube remains coupled to the sampling device. This system also permits cleaning, sampling and desorption of the sample tubes without removing the sample tubes from the system. Because of its construction, only one sample tube can be desorbed at a time; no additional sample tubes are provided in the overall unit; the individual sample tubes are not easily replaced; and the entire unit cannot be placed back in service until all of the individual tubes are desorbed and analyzed.
Another existing unit in the field is the HAPSITE field portable mass spectrometer unit which uses a single collector tube to acquire samples for trace analysis. In the field, sampling/analysis turnaround time and battery power limit the user of this device to acquiring only 7 or 8 samples total per battery charge. Also, importantly, since the HAPSITE device includes only a single concentrator tube, only one sample at a time can be taken. Once a sample is taken, the HAPSITE sample must be analyzed before the single concentrator tube can be cleaned and desorbed for taking another sample. In addition, the HAPSITE unit's bulk and the necessity to analyze the samples on site limit the user's mobility and prolongs the exposure of field personnel to potentially hazardous environments.
It is therefore desirable to provide a portable multi-tube air sampling unit which is capable of acquiring multiple samples using an improved manifold design which minimizes the length of the sample path and which includes a hinged retainer bar mechanism which allows for relatively quick and easy removal and replacement of the various sample tubes so that more samples can be collected without waiting for the first batch of samples to be analyzed. This will allow the sampling unit to return to the field while the contaminants collected in the previous batch of tubes are still being analyzed at a remote location.
It is also desirable to provide a portable multi-tube air sampler unit which includes a removable plug-in controller device which can be installed on the outside of the unit for controlling the operation of the sampling protocol. It is also desirable to provide a unit wherein the sample acquisition times can be reduced so as to minimize exposure of field personnel to potentially hazardous situations.
Accordingly, the present invention is directed to a portable multi-tube air sampling device which overcomes one or more of the problems set forth above.